http://hdl.handle.net/20.500.12416/4838 Kimya Bilim Dalı yayınlarını içerir. Wed, 28 Oct 2026 17:48:11 GMT 2026-10-28T17:48:11Z http://hdl.handle.net/20.500.12416/8510 Pyrrolizine-3-ones: Synthesis and evaluation of photophysical properties Isik Tasgin, Dilek; Bayraktar, Irem We describe a synthetic approach for pyrrolizine-3-one derivatives and their photophysical properties. These compounds are prepared by a series of reactions employing the substituted pyrroles in one-pot, two-step oxidation, and intramolecular cyclization processes. The photophysical properties of the synthesized compounds were studied by using UV–Vis and fluorescence spectroscopy in different solvents. Maximum absorbance peaks were observed around 306–416 nm and maximum fluorescence emission around 603–614 nm and 465–498 nm for pyrrolyl and N-methyl pyrrolyl substituents, respectively. The introduction of a pyrrolyl substituent had a significant impact on the Stokes shifts (192–206 nm) and quantum yield values ranged from 0.002 to 0.046. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/20.500.12416/8510 2024-01-01T00:00:00Z http://hdl.handle.net/20.500.12416/8449 Development of a selective wet-chemical etchant for precise 3D sculpting of silicon enabled by infrared non-linear laser modification Zolfaghari Borra, Mona; Radfar, Behrad; Nasser, Hisham; Çolakoğlu, Tahir; Tokel, Onur; Turnalı, Ahmet; Demirtaş, Merve; Işık Taşgın, Dilek; Üstünel, Hande; Toffoli, Daniele; İlday, Fatih Ömer; Turan, Raşit Recently-demonstrated high-quality three-dimensional (3D) subsurface laser processing inside crystalline silicon (c-Si) wafers opens a door to a wide range of novel applications in multidisciplinary research areas. Using this technique, novel maskless micro-pillars with precise control on the surface reflection and coverage are successfully fabricated by etching the laser-processed region of the c-Si wafer. To achieve this, a particular selective wet chemical etching is developed to follow subsurface laser processing of c-Si to reveal the desired 3D structures with smooth surfaces. Here, we report the development of a novel chromium-free chemical etching recipe based on copper nitrate, which yields substantially smooth surfaces at a high etch rate and selectivity on the both laser-processed Si surface and subsurface, i.e., without significant etching of the unmodified Si. Our results show that the etch rate and surface morphology are interrelated and strongly influenced by the composition of the adopted etching solution. After an extensive compositional study performed at room temperature, we identify an etchant with a selectivity of over 1600 times for laser-modified Si with respect to unmodified Si. We also support our findings using density functional theory calculations of HF and Cu adsorption energies, indicating significant diversity on the c-Si and laser-modified surfaces. Sun, 01 Sep 2024 00:00:00 GMT http://hdl.handle.net/20.500.12416/8449 2024-09-01T00:00:00Z http://hdl.handle.net/20.500.12416/7273 A Theoretical Investigation: Effect of Structural Modifications on Molecular, Electronic, and Optical Properties of Phosphonate Substituted BODIPY Dyes Tasgin, Dilek Isik; Sirin, Pınar Seyitdanlioglu Phosphonates are important organophosphorus compounds which exhibit versatile properties in organic chemistry, medicinal chemistry, materials and biological applications. Phosphonate groups have appeared in a very few examples of BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) compounds that are important florescent dyes in these areas. The deficiency in the area motivated us to investigate how the phosphonate substituent(s) affect the structural, electronic, and optical properties of meso, α, or α, α′-substituted BODIPYs using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. We have identified the suitable method as HSEH1PBE functional in combination with the basis set 6-31+G** by comparing the theoretical results with the experimental studies. Structural, electronic and optical parameters of a series of designed phosphonate substituted 12 BODIPYs (1-4) have been investigated. The α, and α, α′-vinyl phosphonate substituted BODIPYs (3,4) compared to meso-substituted BODIPYs (1,2) have both lower HOMO/LUMO electronic energies [(−5.57)-(−6.19)/(−3.16)-(−3.91)] and lower electronic energy gaps (Egap) (2.11–2.42). Electrostatic potential analysis was performed for all BODIPYs to characterize their electron distribution and TD-DFT analysis was used for the absorption spectral analysis. The presented theoretical approach can be a practical guide for experimental studies for the design of new BODIPY compounds with desired properties. Thu, 20 May 2021 00:00:00 GMT http://hdl.handle.net/20.500.12416/7273 2021-05-20T00:00:00Z http://hdl.handle.net/20.500.12416/4857 The Design, Synthesis and Spectroscopic/Photophysical Characterization of Phosphonate-substituted BODIPY Taşgın, Dilek Işık BODIPY compounds continue to attract the attention of scientists from multidisciplinary areas because of the wide range applications and excellent photophysical properties as fluorescent sensors or dyes. In this study, a new phosphonate substituted BODIPY dye was synthesized by classical condensation-oxidation-complexation method of pyrrolic compounds and aldehyde. The structure and photophysical properties of the synthesized BODIPY compound were determined by 1H NMR, 13C NMR, 31P NMR, 19F NMR, UV-Vis absorption and fluorescence spectroscopic techniques. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/20.500.12416/4857 2020-01-01T00:00:00Z